1. Field of the Invention
The present invention relates generally to metal production and, in certain embodiments, relates to methods of producing metallic tubular bars having high strength while concurrently possessing good toughness.
2. Description of the Related Art
Seamless steel tubes are widely used in a variety of industrial applications. Due to requirements for higher load bearing capacity, situations of dynamic stresses, and the need for lighter components, there is an increasing demand for the development of steel tubes possessing increased strength and toughness.
In the oil industry, perforating guns comprising steel tubes containing explosive charges are used to deliver explosive charges to selected locations of wells. The steel tubes used as perforating gun carriers are subjected to very high external collapse loads that are exerted by the hydrostatic well pressure. On the other hand, during detonation, the steel tubes are also subjected to very high dynamic loads. To address this issue, efforts have been directed to the development of steel tubes with high strength, while at the same time maintaining very good impact toughness.
At present, the highest available steel grade in the market has a minimum yield strength of about 155 ksi. As a result, thick walled tubes are often employed in certain formations in order to withstand the high collapse pressures present. However, the use of thick walled tubes significantly reduces the working space available for the explosive charges, which may limit the range of applications in which the tubes may be employed.
From the foregoing, then, there is a need for improved compositions for metallic tubular bars, and, in particular, systems and methods for producing metallic tubular bars with a combination of high tensile properties and toughness.